Recombinant Haemophilus influenzae Phosphate transport system permease protein pstC (pstC)
Description
Primary Structure
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Amino Acid Sequence: Full-length protein (1–315 residues) with the sequence:
MLTKSRKYFNQTWIESLFKQTTALFALLVFILLAAILISLVIGSWESIKRFGGSFLLETY WDPVQEQYGAIIPILGTLITAGIALFIAVPISFGIAIFLTELAPNWLKRPISIAIEMLAA IPSIIYGMWGLFVFVPLFQEHIQPVLIDNLGNLPGLELFFSGVPFGVGLFTAGLVLAIMI IPFIASVMRDVFSIVPPMLKEGAYGLGATTWEVVRQVIVPHTRIGLVGSVMLGLGRALGE TMAITFIIGNSFQLPNSLFSPSTSIASAIANEFNEAGGLQKSALMELGLLLFVITTMVLI LSRLMITKMQQTKGK. -
Post-Translational Modifications: Expressed with an N-terminal His tag for purification; lacks native lipid modifications due to recombinant engineering .
Physicochemical Properties
| Property | Specification |
|---|---|
| Molecular Weight | ~35 kDa (calculated) |
| Purity | >90% (SDS-PAGE verified) |
| Expression System | Escherichia coli |
| Tag | Polyhistidine (His-tag) |
| Storage Form | Lyophilized powder in Tris/PBS buffer |
| Stability | Stable at -80°C; avoid freeze-thaw |
Functional Role in Phosphate Transport
PstC is an integral membrane permease subunit of the PstSCAB system, which operates as follows:
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Mechanism: Collaborates with PstS (Pi-binding protein), PstA (permease), and PstB (ATPase) to form a high-affinity Pi transporter .
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Critical Residues: Mutations in conserved regions (e.g., Arg-237, Glu-240) disrupt Pi transport but retain regulatory functions (e.g., Pho regulon repression) .
Key Findings from Genetic Studies:
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Frameshift mutations in pstC (e.g., in Rhizobium meliloti) impair Pi uptake and nitrogen fixation, highlighting its essential role in bacterial metabolism .
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Deletion of pstC in Escherichia coli results in constitutive alkaline phosphatase activity, indicating loss of Pi sensing .
Recombinant Expression
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Vector System: T7 promoter-driven expression in E. coli (e.g., BL21 strains) .
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Purification: Affinity chromatography (Ni-NTA resin) followed by gel filtration; yields >0.1 mg/mL post-reconstitution .
Research Applications
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Structural Studies: Used in SDS-PAGE and Western blotting for membrane protein analysis .
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Functional Assays:
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Biotechnological Use: Antigen in ELISA for antibody development .
Comparative Analysis of PstC Homologs
Challenges and Future Directions
Product Specs
Note: While we prioritize shipping the format currently in stock, we are happy to accommodate specific format requests. Please indicate your preferred format in the order notes, and we will fulfill your requirement.
Note: All our proteins are shipped with standard blue ice packs. Should you require dry ice shipping, please communicate this requirement in advance as additional fees will apply.
Generally, the shelf life of liquid form is 6 months at -20°C/-80°C. Lyophilized form, on the other hand, has a shelf life of 12 months at -20°C/-80°C.
Target Background
KEGG: hin:HI1382
STRING: 71421.HI1382
Q&A
Basic Research Questions
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What is the functional role of PstC in Haemophilus influenzae?
PstC functions as an integral membrane component of the PstSCAB phosphate transport system in H. influenzae. This high-affinity, ATP-dependent transport system is critical for phosphate acquisition, particularly in phosphate-limited environments. In the PstSCAB complex, PstC works alongside PstA as a transmembrane permease component, forming the channel through which phosphate is transported into the bacterial cell .
The complete system consists of PstS (the periplasmic phosphate-binding protein), PstC and PstA (the integral membrane proteins forming the transport channel), and PstB (the ATP-binding protein that provides energy for transport) . This system is particularly important for bacterial survival in phosphate-limited environments and may play roles in virulence and adaptation to host environments.
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How is the PstSCAB system regulated in bacteria?
Research indicates that the PstSCAB system in bacteria is typically regulated by the two-component PhoBR regulatory system. In Sinorhizobium meliloti, for example, the pstSCAB genes and the regulatory phoUB genes are transcribed from a single promoter containing two PhoB binding sites, with transcription requiring PhoB .
Under phosphate-sufficient conditions, PhoB remains inactive, and the low-affinity phosphate transport systems (like Pit) are expressed. Under phosphate-limiting conditions, PhoB becomes activated through phosphorylation, inducing expression of the high-affinity PstSCAB system while repressing other phosphate transport systems .
Methodology to study this regulation typically involves:
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Creating reporter gene fusions (e.g., lacZ fusions) to monitor transcriptional activity
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Constructing deletion mutants in regulatory genes
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Performing phosphate starvation experiments under controlled conditions
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Measuring gene expression using qRT-PCR or RNA-seq approaches
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